The invention relates to an inclined-axis variable displacement motor and an inclined-axis variable displacement pump or an axial piston machine of inclined-axis construction.
The generally known operating principle of such machines is based on an oil-volume stream being converted into a rotary movement.
The prior art discloses an axial piston machine in which a cylinder block which is pivoted in relation to the axis of the output shaft is arranged on an adjustable valve segment. By way of this valve segment, the hydraulic oil, as operating fluid, is directed from the cylinder block into the stationary end housing of the motor. This solution has the inherent disadvantage that, on account of the design, the throughflow cross sections between the adjustable valve segment and the end housing cannot be of large enough design, which is then associated with corresponding energy losses in the case of relatively high throughflow volumes of the flowing operating fluid. In this prior-art solution, a detrimental effect is produced by the abovementioned limitation in the throughflow cross sections even with a maximum pivoting angle of the axis of the cylinder block in relation to the axis of the output shaft. This limitation basically increases as the pivoting angle increases. A further disadvantage of such piston machines is that the maximum value of the pivoting angle cannot readily be increased since this results in the dimensions and the design of such a piston machine having to meet more stringent requirements which, from certain limits, is no longer acceptable from a technical or commercial viewpoint.
Within the context of a further prior-art solution of such axial piston machines, the cylinder block is mounted in a pivoting body which, in turn, is mounted in the housing on two pins by a radial rolling-contact bearing. These pins have channels which pass through the pins and through it the hydraulic oil can flow from the pivoting body into the stationary part of the housing either in the axial direction or in the radial direction around the entire circumference of the pins. Such an inclined-axis variable displacement motor requires greater installation dimensions precisely in the region of the mounting of the pivoting body and in the region of the distribution of the operating fluid. Furthermore, its practical use is limited by the weight and the increased material consumption.
Patent DE 198 33 711 discloses a solution for an inclined-axis variable displacement motor, in which a movable intermediate plate is arranged between a valve segment and the functionally connected stationary part of the motor housing. The position of this intermediate plate is synchronized relative to the valve segment and to the stationary part of the motor housing via a mechanism which has three pins and is mounted on both sides of said valve segment. With smaller values of the maximum possible pivoting angle of the cylinder block, this configuration of an axial piston machine can, in part, eliminate the disadvantages from the abovementioned prior art. However, this entails, at the same time, an undesirable increase in the production costs, in the weight and in the design outlay for such a piston machine.
Therefore the principal object of the present invention is to provide an inclined-axis variable displacement unit or an axial piston machine of inclined-axis construction in which the mounting of the pivoting body does not limit, or even prevent, the transfer and/or introduction of the operating fluid in much higher pivoting-angle ranges.
The essential principle realized by the invention is based on a hydrostatic slide mounting of the pivoting body within the housing of the unit, additional bearing components, such as pins, rolling-contact bearings, or the like, being completely dispensed with.
The pivoting body is divided into two corresponding symmetrical cylinder segments which are arranged on both sides of the axis of rotation of the cylinder block, which is mounted axially in the pivoting body. In those surfaces directed towards the housing, said cylinder segments are mounted in corresponding recesses or bowl-like hollows in the inner surface of the housing. Located between the hollows and the bearing surfaces of the symmetrical cylinder segments, for the purpose of forming the hydrostatic slide mounting, is a corresponding oil layer.
In a preferred embodiment of the inclined-axis variable displacement unit according to the invention, the hollows are arranged in the inner surface of the housing at a location in which an imaginary cylinder plane which is defined jointly by; the outer cylinder surfaces of the opposite cylinder segments intersects the cylinder block, which is mounted axially in the pivoting body, in a plane which is located just beneath that end side of the cylinder block which is directed towards the output shaft, in the region of the mounting of the working pistons in said cylinder block.
Each cylinder segment has, in its cylindrical part, a throughflow chamber and a compensation chamber, which are enclosed by sealing edges or sealing zones. Corresponding throughflow chambers open out into the hollows forming the mounting. In the region of the mounting according to the invention, the throughflow chambers of the hollows are connected to the throughflow chambers of the cylinder segments. This ensures that the transfer and/or introduction of the hydraulic oil, as operating fluid, takes place in the region of the mounting, in which case the operating fluid then serves, at the same time, as hydrostatic sliding fluid.
Stationary transfer channels are arranged in the housing and open out into the corresponding throughflow chambers of the concave cylindrical hollows.
Correspondingly, the throughflow chambers of the cylinder segments are connected to non-stationary transfer channels. Circle-segment channels are arranged in the base of the pivoting body, the non-stationary transfer channels opening out into said circle-segment channels on the side correspondingly associated with the latter.
Each compensation chamber may be connected via a corresponding connecting channel, either to a non-stationary transfer channel or to a circle-segment channel which, as seen relative to the axis of rotation of the cylinder block, is located on the side opposite to the corresponding cylinder segment.
In a preferred embodiment of the inclined-axis variable displacement unit according to the invention, said non-stationary transfer channels are each formed from two channels which run essentially parallel to one another.
The base of the pivoting body preferably has a trapezoidal cross section in the plane which is defined by the axis of rotation of the cylinder block, on the one hand, and by the axis of the output shaft, on the other hand.
The output shaft of said inclined-axis variable displacement unit according to the invention is mounted in the housing by a first rolling-contact bearing and a second rolling-contact bearing, the first rolling-contact bearing being located in the side directed towards the pivoting body. According to the invention, the end plane of the outer race of the first rolling-contact bearing is located in a separating plane of the two-part housing.